Meet Kazuki Shikimori, a 17-year-old enrolled at Aoi Academy, renowned for training exceptional magicians. Here, each sorcerer faces a critical limitation on spells; exceeding this quota results in a perilous transformation into dust. Kazuki, however, possesses an unusually low spell capacity compared to his peers. His uneventful life takes a dramatic turn when three mysterious girls materialize before him, their sights set on a unique prize—his very genes. Unbeknownst to Kazuki, their arrival heralds a sinister fate, for his dwindling magical reserves hint at a looming catastrophe.